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Biology subjects

Chen, M.

Publications and source records attributed to Chen, M..

At least 181 records · Page 10Linked to original sources

DiffPIE: Guiding Deep Generative Models to Explore Protein Conformations under External Interactions

In recent years, many foundation generative models have been developed to pre-dict structures of molecules and materials. Although these foundation models have achieved great success, it is challenging to collect enough data to train foundation generative models. One such example is to predict protein conformations with protein-environmental interactions (PEI), such as interactions introduced by organic linkers or material surfaces. We propose a physics-guided route to extrapolate foundation mod-els beyond their training domain. Our method couples a pretrained deep generative model with explicit, physics-based interaction potentials for PEI, steering sampling to-ward conformations consistent with external constraints without any retraining or fine-tuning. We demonstrate accurate and efficient conformation prediction of (i) cyclic peptide with organic linkers and (ii) peptide adsorbed on the gold surface. The gen-erated structures serve as high-quality initial conditions for downstream simulations, providing a general, systematic approach to extend foundation models to proteins under system-specific environmental interactions.

biophysics↗

A unified eIF1A+ luminal cells-centered hypoxic and "cold" tumor microenvironment promotes PCa progression among different subtypes

PCa is a malignancy with high heterogeneity arises from both tumor microenvironment (TME) and histological subtypes. To achieve superior clinical efficacy, it is imperative to identify unified progression drivers within such heterogeneity in PCa, thereby enabling the development of more consistent and effective therapeutic strategies. In this study, we applied imaging mass cytometry to stain 39 proteins on 71 tissues comprising para-cancer, low-grade acinar adenocarcinoma (LgPAC), high-grade PAC (HgPAC), intraductal carcinoma (IDC) and ductal adenocarcinoma (DAC) tissues, obtaining the spatial proteomic landscape of 345,233 single cells. We discovered a hypoxic eIF1A+ luminal epithelial (LE) cluster exhibiting both translational activation and immunosuppressive properties, which was enriched in high-risk PCa including HgPAC, IDC and DAC, and associated which tumor progression and unfavorable prognosis. Additionally, eIF1A+ LE orchestrates the formation of an immunologically "cold" TME, characterized by the low infiltration of anti-cancer immune cells including PD1- T cells CD163- macrophages. Through in vivo validation and investigator-initiated study, we further found that Homoharringtonine, an inhibitor targeting protein translation process, effectively inhibited PCa growth, alleviated hypoxic microenvironment, and enhanced immune cell infiltration. This study is the first to apply spatial proteomics to delineate consistent molecular features across histological subtypes, providing transformative insights for clinical management of PCa.

cancer biology↗

Regulation of the MDM2-p53 Nexus by a Nuclear Phosphoinositide and Small Heat Shock Protein Complex

The tumor suppressor p53 maintains genome stability in the setting of cellular stress and is frequently mutated in cancer. The stability of p53 is regulated by its interaction with the oncoprotein MDM2, a ubiquitin E3 ligase. Recently, nuclear phosphoinositides were reported to bind and stabilize p53. Here, we report that genotoxic stress induces the type I phosphatidylinositol phosphate kinase (PIPKI) and its product phosphatidylinositol 4,5-bisphosphate (PIP2) to bind and regulate the stability and function of MDM2. Following genotoxic stress, nuclear PIPKI binds to MDM2 to generate a complex of MDM2 and PIP2. PIP2 binding to MDM2 differentially regulates the recruitment of the small heat shock proteins (sHSPs) B-crystallin (BC) and HSP27 to the MDM2-PIP2 complex, acting as an on-off switch that regulates MDM2 stability, downstream targets, ubiquitination activity, and interaction with p53. Our results demonstrate an unexpected role for nuclear phosphoinositides conferring specificity to the MDM2-PIP2-sHSPs association. Notably, the differential engagement of BC and HSP27 reveals that sHSPs are not merely passive chaperones but play active, selective roles in fine-tuning MDM2 function and MDM2-p53 nexus. These findings provide a novel therapeutic strategy for targeting this pathway in cancer.

cancer biology↗

Functional landscape of circular RNAs in human cancer cells

Circular RNAs (circRNAs) constitute a novel class of noncoding RNAs showcasing distinct tissue- and cell-specific expression patterns. Despite the extensive profiling of circRNAs, their individual functions remain poorly understood. To fill this gap, we designed a genome-wide library of 65,300 shRNAs, targeting 9,663 clinically relevant circRNAs and 3,981 of their linear parental genes, and conducted functional screening in seven types of human cancer. We identified a total of 1,342 essential circRNAs (13.9% screened) that impact cell proliferation in at least one cell line, and in 96.5% of the cases, the linear counterparts are not essential. While a shared common subset emerges as functional regulators across all examined cell lines, the majority of circRNAs are functional in a cell type-specific manner. For a comprehensive presentation of the functional circRNA landscape in cancer, we introduce FunCirc, an online database encompassing functional circRNAs across cancer cell lines, coupled with circRNA expression profiles from diverse cancer and tissue types. Our work enhances the understanding of circRNA functions in cancer and provides the scientific community with a resource to further investigate their intricate roles.

cancer biology↗

Effects of Exercise and Konjac on Lipid Metabolism and Mechanism in Obese Rats

ObjectiveTo study the effects of exercise and konjac on body weight and lipid metabolism in obese rats, and the possible mechanism of exercise combined with konjac on body weight and lipid metabolism. MethodsFifty male Sprague Dawley rats were randomly divided into 5 groups. After six weeks of intervention, blood lipid, body weight, liver weight, inflammatory factors, oxidative stress markers and proteins were measured. ResultsWeight and liver weight in HFD group were significantly higher (P<0.05, P<0.01) than those in CON group. Compared with HFD group, blood lipid index in intervention group were significantly decreased; The levels of MDA (P<0.01, P<0.05, P<0.05) and SOD (P<0.05) in intervention group were significantly decreased; the GSH levels in HAE group and HKE group were significantly increased(P<0.01, P<0.05); the levels of IL-6, TNF-, and leptin in HAE group (P<0.05, P<0.05, P<0.01) and HKE group (P<0.01, P<0.01, P<0.05) were significantly decreased; ApoA5 in intervention group was significantly increased (P<0.01), SREBP-1c and LXR was significantly decreased (P<0.01). ConclusionKonjac or exercise alone can improve the lipid metabolism, and the comprehensive effect is better. The mechanism of regulating lipid metabolism may be related to the expression of LXR, SREBP-1c and ApoA5.

biochemistry↗

Circular RNA profiling and functional screening in breast cancer identify circNSD1 as a suppressor of tumor autophagy

Circular RNAs (circRNAs) have emerged as critical regulators of cell biology. However, their function in breast cancer remains elusive. Herein, through circRNA profiling of 38 breast tumors and 10 benign breast tissues, we identified 509 of differentially expressed circRNAs. Integration with transcriptome-wide functional screening of approximately 10,000 circRNAs pinpointed circNSD1(6) as a top ranked tumor suppressor in breast cancer. circNSD1(6) is downregulated in tumors and suppression of the circular form, but not the linear form, promotes breast cancer proliferation and tumor growth. Mechanistically, circNSD1(6) interacts with autophagy receptor SQSTM1/p62 and inhibits the oligomerization of p62, thereby suppressing p62 body formation and p62-dependent autophagy. Furthermore, circNSD1(6) ameliorates p62-mediated Keap1 sequestration, hence suppresses the Nrf2 pathway and oxidative stress tolerance. Our study provides a landscape view of the transcription and function of circRNA in breast cancer, and uncovers the crucial role of circNSD1(6) in autophagy and antioxidant stress.

cancer biology↗

A method for the detection and enrichment of endogenous cereblon substrates

C-Terminal cyclic imides are posttranslational modifications on proteins that are recognized and removed by the E3 ligase substrate adapter cereblon (CRBN). Despite the observation of these modifications across the proteome by mass spectrometry-based proteomics, an orthogonal and generalizable method to visualize the C-terminal cyclic imide would enhance detection, sensitivity, and throughput of endogenous CRBN substrate characterization. Here we develop an antibody-like reagent, termed "cerebody," for visualizing and enriching C-terminal cyclic imide-modified proteins. We describe the engineering of CRBN derivatives to produce cerebody and use it to identify CRBN substrates by Western blot and enrichment from whole cell and tissue lysates. CRBN substrates identified by cerebody enrichment are mapped, validated, and further characterized for dependence on the C-terminal cyclic imide modification. These methods will accelerate the characterization of endogenous CRBN substrates and their regulation.

biochemistry↗

Improved Prediction of Bacterial Type VI Secretion Effector Proteins Using an Integrated Convolutional Neural Network Model Combining N-terminal Signal Sequences, Evolutionary Information and Pre-Trained Protein Language Features

Type VI secretion system effectors (T6SEs) are crucial for bacterial pathogenicity, making their accurate identification essential for understanding bacterial virulence mechanisms. This study analyzed the differences in amino acid composition of N-terminal signal sequences between T6SEs and non-T6SEs, uncovering distinct positional amino acid preferences in T6SEs. Using a combination of unsupervised and supervised analysis, we evaluated feature encoding methods and developed T6CNN, an ensemble model that integrates N-terminal signal sequences, evolutionary information, and pre-trained protein language features for T6SE prediction. T6CNN demonstrated outstanding performance in independent testing, outperforming existing tools with a 7.9% accuracy increase (to 0.953), a 13.2% sensitivity improvement (to 0.964), and a 6.6% specificity enhancement (to 0.951). The T6CNN model offers a reliable and accurate solution for T6SE prediction, with significant potential to advance research on bacterial pathogenicity. ImportanceThis study introduces T6CNN, a new computational model for identifying Type VI secretion system effectors used by harmful bacteria. By analyzing early protein sequences, T6CNN uncovers unique features that reliably distinguish effector proteins. Integrating evolutionary data and pre-trained protein language features, the model outperforms existing methods in accuracy, sensitivity, and specificity. This enhanced prediction tool deepens our understanding of bacterial infection mechanisms and offers researchers a valuable resource for pinpointing key virulence factors. Ultimately, T6CNN may help drive the development of more targeted antibacterial treatments and strategies to combat bacterial diseases.

bioinformatics↗

A rapidly prototyped, simple yet versatile dynamic breathing Exposure-on-a-Chip for investigating nanoparticle deposition in the alveoli

We developed and characterized a three-layer microfluidic Exposure-on-a-Chip (EOC) model to replicate the alveolar microenvironment and simulate breathing motions, offering a physiologically relevant platform for studying inhaled nanomedicines. The EOC chip, fabricated from biocompatible polydimethylsiloxane (PDMS), features a fluidic chamber for cell culture, a pneumatic chamber for pressure application, and a thin PDMS membrane (150 {micro}m) separating the chambers to support cell growth and enable mechanical stretching. Xurography and 3D printing were validated as efficient and reproducible fabrication methods. Mechanical characterization, using fluorescent bead tracing, confirmed that the PDMS membrane accurately mimics alveolar breathing motions under physiological conditions (1-8% strain). Biological validation showed that alveolar epithelial and endothelial cells cultured on the EOC formed functional monolayers, maintaining barrier integrity under cyclic and static stretching, separately. To study nanoparticle behavior, we examined the deposition of nanoparticles under dynamic stretching versus static conditions. Significantly fewer nanoparticles accumulated in cells under continuous dynamic exposure with stretching compared to static culture, highlighting the critical role of mechanical forces in nanoparticle-cell interactions. The EOC platform provides a robust and scalable tool for evaluating nanomedicine efficacy in dynamic environments, representing a significant advancement in alveolus-on-chip technology.

bioengineering↗

A multi-modal whole-slide image processing pipeline for quantitative mapping of tissue architecture, histopathology, and tissue microenvironment

Multi-modal, multiscale imaging is crucial for quantitative high-content spatial profiling. We present an integrated image processing pipeline for comprehensive tissue analysis that combines quantitative phase microscopy for tissue architecture mapping, hyper-plex fluorescence imaging for immune microenvironment profiling, and whole-slide histopathology. This approach enables detailed morphological mapping of tissue architecture and cell morphology, while simultaneously linking them to the functional states of individual cells across the entire slide. By analyzing tissue biopsies from patients with ulcerative colitis, we demonstrate the potential of this pipeline for quantitative spatial analysis of molecular markers related to mucosal healing. Open-source and compatible with conventional microscopy systems, this pipeline provides a powerful tool for research and clinical applications through its comprehensive integration of quantitative, high-content, and histological imaging modalities.

bioinformatics↗

Composition and RNA binding specificity of metazoan RNase MRP

Ribonuclease (RNase) MRP is a conserved RNA-based enzyme that is essential for maturation of ribosomal RNA (rRNA) in eukaryotes. However, the composition and RNA substrate specificity of this multisubunit ribonucleoprotein complex in higher eukaryotes remain a mystery. Here, we identify NEPRO and C18ORF21 as constitutive subunits of metazoan RNase MRP. Both proteins are specific to RNase MRP and are the only ones distinguishing this enzyme from the closely related RNase P, which selectively cleaves transfer RNA-like substrates. We find that NEPRO and C18ORF21 each form a complex with all other subunits of RNase MRP, stabilize its catalytic RNA, and are required for rRNA maturation and cell proliferation. We harness our discovery to identify a full suite of in vivo RNA targets of each enzyme, including positions of potential cleavage sites at nucleotide resolution. These findings resolve the general composition of metazoan RNase MRP, illuminate its RNA binding specificity, and provide valuable assets for functional exploration of this essential eukaryotic enzyme.

molecular biology↗

Reference-based chemical-genetic interaction profiling to elucidate small molecule mechanism of action in Mycobacterium tuberculosis

In an era of increasing resistance, new and effective strategies are needed for antibiotic discovery. Whole-cell active screens yield candidate compounds lacking mechanism-of-action (MOA) information and thus do not provide biological insight for prioritization. We previously reported PROSPECT (PRimary screening Of Strains to Prioritize Expanded Chemistry and Targets), an antimicrobial discovery strategy that measures chemical-genetic interactions between small molecules and a pool of Mycobacterium tuberculosis mutants, each depleted of a different essential protein target. PROSPECT facilitates efficient hit prioritization by simultaneously identifying whole-cell active compounds with high sensitivity and providing early insights into their MOA. Here, we report a reference-based approach to infer MOA from often complex PROSPECT data. For this aim, we curated a reference set of 437 compounds with published, annotated MOA and known or suspected antitubercular activity, and applied PROSPECT to it. We then developed Perturbagen CLass (PCL) analysis, a computational method that predicts MOA by comparing chemical-genetic interaction profiles of unknown compounds to those of this reference set. In leave-one-out cross-validation, PCL analysis correctly predicted MOA with 70% sensitivity and 75% precision. When applied to 75 antitubercular leads with known MOA previously reported by GlaxoSmithKline (GSK), PCL analysis similarly achieved 69% sensitivity and 87% precision. We also analyzed 98 GSK compounds lacking MOA information, predicting 60 of them to act via a reference MOA, and followed up with functional validation of 29 compounds predicted to target respiration-related MOAs. Finally, we applied PROSPECT and PCL analysis to [~]5,000 compounds from larger unbiased libraries that had not been preselected for antitubercular activity. PCL analysis identified a novel scaffold lacking wild-type activity but predicted to inhibit respiration via QcrB, and we confirmed this prediction while chemically optimizing this scaffold to achieve wild-type activity. PCL analysis of PROSPECT data thus enables rapid MOA assignment and hit prioritization, advancing the discovery of new, potent antitubercular compounds.

microbiology↗

In Silico Discovery of Small Molecule Modulators Targeting Ebola Virus VP 35 and VP 40 protein

Ebola virus (EBoV) proteins VP35 and VP40 are acknowledged as significant pharmacological targets for disrupting viral replication, virion assembly, and the budding process from host cells. We employed molecular docking based throughput virtual screening (HTVS), standard precision (SP), and extra precision (XP) docking to discover candidate compounds. Subsequently, molecular dynamics simulations, and ADMET analyses to identify potential small molecular compounds that could inhibit the Ebola virus. Among 210,590 compounds from the SPECS database, we found the compounds AO-022/43452438, AN-465/43369333, and AN-465/43369198 were optimal candidates for the EBOV-VP35 protein, while AN-465/43369160, AN-465/4341136, and AN-465/43369952 also emerged as optimal compounds for the EBOV-VP40 protein. Furthermore, we employed the energy decomposition technique, MM-GB/SA, to identify the top ten amino acids that significantly contribute to the binding interactions. ADMET result implicated that the six compounds have potential druggability, but special attention should be given to AN-465/43369333 due to potential cardiac toxicity. In conclusions, the six compounds and their key interacting amino acid sites identified in this study may serve as a valuable platform for the future development of novel therapeutics targeting the Ebola virus.

bioinformatics↗

Multivalency controls the growth and dynamics of a biomolecular condensate

Biomolecular condensates are essential for cellular organization and function, yet understanding how chemical and physical factors govern their formation and dynamics has been limited by a lack of non-invasive measurement techniques. Conventional microscopy methods often rely on fluorescent labeling and sub-strate immobilization, which can perturb the intrinsic properties of condensates. To overcome these challenges, we apply label-free, contact-free holographic video microscopy to study the behavior of a condensate-forming protein in vitro. This technique enables rapid, high-throughput, and precise measurements of individual condensate diameters and refractive indexes, providing unprecedented insight into size distributions and dense-phase macromolecular concentrations over time. Using this method, we investigate the kinetics of droplet growth, aging, and equilibrium dynamics in the model condensate-forming protein PopZ. By systematically varying the concentration and valence of cations, we uncover how multivalent ions influence condensate organization and dynamics, a hypothesis we further test using super-resolution microscopy. Our findings reveal that PopZ droplet growth deviates from classical models such as Smoluchowski coalescence and Ostwald ripening. Instead, we show that condensate growth is consistent with gelation at the critical overlap concentration. Holographic microscopy offers significant advantages over traditional techniques, such as differential interference contrast (DIC) microscopy, delivering reproducible measurements and capturing condensate dynamics with unparalleled precision. This work highlights the power of holographic microscopy to probe the material properties and mechanistic underpinnings of biomolecular condensates, paving the way for deeper insights into their roles in synthetic systems.

biophysics↗

ZUGC-RNA degradation generates immunosuppressor to evade immune responses in eukaryotes

Among the hundreds of modified nucleosides identified in terrestrial life, 2-amino-6-aminopurine (Z) is widely recognized as a prominent modified purine. Recently, RNA written with the ZUGC alphabet shows significant potential in RNA therapeutics as a synthetic biosystem. Here, we demonstrate that ZUGC-RNA can evade immune recognition in eukaryotes, independent of factors such as RNA length, sequence, 5-triphosphate, modified uridine, and secondary structure. Notably, we discovered that both the degradation of ZUGC-RNA and metabolites of Z-nucleotides can function as immunosuppressors, silencing TLR7 sensing to block immune responses. This mechanism differs from that of pseudo-uridine ({Psi}) modified RNA currently in use. ZUGC-RNAs also demonstrate broad applicability across multiple neural cell types. Our findings provide valuable insights for developing more tolerable RNA-based drugs and designing immunomodulators targeting TLR7. In addition to the potential prebiotic relevance of Z, our finding not only contributes to understanding the RNA world hypothesis but also provides new insights into the exploration of the origin of life.

synthetic biology↗

ESMAdam: a plug-and-play all-purpose protein ensemble generator

Proteins often adopt multiple ensemble conformations to perform essential functions such as catalysis, transport, and signal transduction. Traditional physics-based methods for generating these conformations, including molecular dynamics and Monte Carlo simulations, are computationally expensive and time-consuming, limiting their practicality for high-throughput applications like screening. Recent advances in machine learning, particularly deep generative models, offer a promising alternative for protein conformation ensemble generation. However, these models are often task-specific or rely on strong assumptions to generalize. Here, we introduce ESMAdam, a versatile and efficient framework for protein conformation ensemble generation. Using the ESMFold protein language model ESMFold and ADAM stochastic optimization in the continuous protein embedding space, ESMAdam addresses a wide range of ensemble generation tasks. In this work, we demonstrate several basic applications of ESMAdam, including conditional ensemble generation and CG-to-all-atom backmapping. In addition, we showcase advanced applications, such as screening alternative binding modes of protein multimers and reconstructing 3D structures from cryo-EM images. Compared to traditional physics-based methods, ESMAdam significantly reduces computational time. Unlike deep-generative-model-based approaches, it requires no retraining and easily adapts to diverse ensemble restraint conditions, making it exceptionally suited for various structure prediction and screening tasks. This plug-and-play framework represents a step toward efficient and flexible protein ensemble generation for applications in structural biology and drug discovery.

biochemistry↗

Elevated SUN1 promotes aging-related polarity defects through mechanical coupling microtubules to the nuclear lamina

In migratory fibroblasts, the front-rear polarity required for cell migration is defined by an anterior centrosome relative to the nucleus. To achieve this polarity, actin cables drive the nucleus backward by coupling to nuclear membrane proteins nesprin-2G and SUN2. Aging disrupts this cell polarity by increasing the protein levels of SUN1, a SUN2 homolog. Here, we investigated the molecular mechanisms behind this disruption and found that the dominant negative effect of SUN1 and progerin, an aging-related lamin A variant, required direct SUN1-lamin A interaction. Microtubule interaction and force transmission through a nesprin, identified as nesprin-2, are crucial for SUN1s effect. We further discovered that stable microtubules are both necessary and sufficient to inhibit cell polarity. Using SUN1-SUN2 chimeric proteins, we demonstrated that the SUN domains determine their roles in cell polarization. Our findings reveal how elevated SUN1 disrupts cell polarity through coupling microtubule and nuclear lamina, emphasizing the impact of altered microtubule stability and nuclear mechanotransduction in aging.

cell biology↗

Enforced E-selectin ligand installation enhances homing and efficacy of adoptively transferred T cells

Adoptive T-cell transfer has revolutionized the treatment of hematological malignancies. However, this approach has had very limited success in treating solid tumors, largely due to inadequate infiltration of vascularly administered T cells at tumor sites. The shear-resistant interaction between endothelial E-selectin and its cognate ligand expressed on leukocytes, sialyl Lewis X (sLeX), is an essential prerequisite for extravasation of circulating leukocytes. Here, we report that enforced E-selectin ligand expression (enforced sLeX display) on antigen-specific T cells can be achieved by fucosylating cells via cell surface treatment with the human 1-3-fucosyltransferase, FUT6 ("exofucosylation"), or via Golgi-targeted FUT6 overexpression ("Golgi-fucosylation"). However, despite comparable E-selectin binding, only sLeX-modified T cells engendered by exofucosylation, not by Golgi-fucosylation, exhibited enhanced parenchymal infiltration of target malignant sites. This heightened homing yielded significantly improved therapeutic efficacy in various murine syngeneic and xenograft cancer models, including subcutaneous solid tumors, lymphoma and leukemia, as well as lung and bone marrow metastases. Therefore, exofucosylation represents a promising strategy to improve the efficacy of adoptive T-cell therapy, particularly in the treatment of solid tumors and metastatic disease.

cancer biology↗